Comprised of religious figures, former lawmakers and officials as well as some incumbent MPs, the critics are also unhappy about Zarif's more moderate foreign policy, including what they call his "reactionary stance towards the bastard (Israeli) Zionist regime and the Holocaust."

The incumbent lawmakers - particularly those in Iran's national security and foreign policy commission - are pressuring Zarif, taking him to the parliament floor and questioning him.

At such a session Tuesday, Zarif spoke about Israel, whose existence Tehran does not recognize, Iranian media reported.